Phenyl raw rubber significantly improves the oxidative degradation resistance of bipolar plates in hydrogen fuel cell stacks through molecular structure optimization and interface stabilization mechanisms, mainly in the following aspects:

I. Molecular Structure Stabilization
* Conjugated Structure Formation: After phenyl groups are introduced into polysiloxane side groups, a stable conjugated structure is formed, which can effectively disperse and consume the energy generated during oxidation, preventing rapid degradation of the molecular chains. This structure allows silicone rubber to maintain the integrity of its molecular chains in oxidizing environments, extending the service life of the bipolar plates.

Enhanced Electron Affinity: Phenyl has a high electron affinity, which can more effectively capture high-energy electrons and reduce the active sites for oxidation reactions. Studies have shown that increasing the phenyl content can significantly improve the breakdown field strength of the material. The breakdown field strength of PMSG-4 (phenyl-modified organosilicon gel) at 150℃ decreased by only 25.38% compared to room temperature, while that of ordinary silicone decreased by 35.42%, indicating that phenyl can effectively maintain the electrical insulation performance of the material in high-temperature oxidizing environments. II. Interfacial Oxide Film Regulation

Oxide Film Structure Optimization: During bipolar plate operation, phenyl raw rubber promotes the formation of a denser and more uniform oxide film, avoiding the unstable structure of "large outer oxide particles + loose inner needle-like oxides" found in traditional materials. This optimized oxide film effectively blocks oxygen and moisture from penetrating into the material, slowing down the oxidation process.

Improved Interfacial Stability: Under high potential on the anode side, the oxide film thickening rate of the phenyl-modified material is significantly reduced. Ordinary metal bipolar plates develop excessively thick oxide films during long-term operation, leading to a significant increase in contact resistance. The phenyl-modified material maintains a more stable interfacial contact resistance, ensuring battery efficiency.

III. Wide Temperature Range Stability Guarantee
Low-Temperature Oxidation Resistance: Phenyl silicone rubber maintains good elasticity at -100℃, with a low-temperature elasticity retention rate of over 90% (elasticity loss <10% at -90℃). This allows the bipolar plate to maintain structural integrity during low-temperature startup and in cold environments, preventing accelerated oxidation caused by low-temperature embrittlement.

High-Temperature Oxidation Resistance: Low-phenyl silicone rubber with a phenyl content of 5-10% can reduce its glass transition temperature to -115℃, while its high-temperature performance is also improved, exhibiting superior resistance above 250℃ compared to ordinary silicone rubber. This wide-temperature-range stability allows bipolar plates to maintain oxidation resistance across a wide operating temperature range in fuel cells.

IV. Practical Application Value
Reduced Corrosion Current Density: Studies show that bipolar plates using phenyl-modified materials can reduce the corrosion current density to 5.9 × 10⁻⁷ A·cm⁻² in simulated fuel cell operating environments, far lower than that of ordinary stainless steel, significantly improving the corrosion resistance of the bipolar plates.

Dynamic Operating Condition Adaptability: In actual fuel cell systems, bipolar plates need to cope with drastic fluctuations in potential, temperature, and pH caused by frequent start-stop cycles and load changes. Phenyl-modified raw rubber materials, with their excellent interfacial stability and wide-temperature-range performance, can effectively resist oxidative degradation caused by these dynamic operating conditions, extending the service life of the bipolar plates.

Cost-effectiveness balance: Compared to precious metal coatings (such as platinum plating), phenyl raw rubber modification is less expensive and simpler to process, while providing similar oxidation resistance, offering an economically viable solution for the commercial application of hydrogen fuel cell bipolar plates.

In summary, phenyl raw rubber significantly enhances the oxidation and degradation resistance of hydrogen fuel cell stack bipolar plates through multiple mechanisms, including optimizing molecular structure, regulating interfacial oxide films, and improving wide-temperature stability, providing key material support for improving the reliability and lifespan of fuel cell systems.